Circuit-breaker.



No. 729,211. PATENTED MAY 26, 1903. G. H. NORWOOD.

CIRCUIT BREAKER.

APPLI OATION FILED NOV. 4, 1899.-

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m: Mann's PETERS 0o, wnrau'mo, wasmrvs'rou. n cy UNITED STATES PatentedMay 26, 1903.

PATENT OFFICE.

CLARENCE H. NORWOOD, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE SIEMENS &HALSKE ELECTRIC COMPANY OF AMERICA, OF CHI- CAGO, ILLINOIS, ACORPORATION OF ILLINOIS.

CIRCUIT-BREAKER.

SPECIFICATION forming part of Letters Patent Nb. 729.21 ated ay 2 1903-Application filed November 4, 1899. Serial No. 735,809. (No model.)

To all whom, it may concern:

Be it known that I, CLARENCE H. NORWOOD, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Circuit-Breakers, (CaseNo. 312,) of which the following is a full, clear, concise, and exactdescription, reference being had to the accompanying drawings, forming apart of this specification.

My invention relates to switches, and more particularly to that class ofswitches known as circuit-breakers, and has for its object the provisionof means whereby circuits are protected both against overloads andunderloads. Certain features of my invention, however, are useful in connection with circuit-breakers that act exclusively on overloads.

As is well known to those skilled'in the art, circuit-breakers areemployed to protect circuits and apparatus against overloads and shortcircuils,.the circuit being opened automatically when the current hasreached a predetermined value. It is important, however, in certainclasses of work to have the circuit opened upon underloads or when thecurrent in the circuit reaches a low or zero value. This is especiallytrue, for example, in the operation of series-wound motor-drivenboosters. If for any reason in the operation of boosters of this classthe motor-circuit be opened while the booster-generator is connected tothe line in which the voltage is to be raised, this generator willreverse and run as a motor and being a series-machine operating on noload will very soon reach a dan gerous speed, which might even becomedisastrous and destroy the machine. In such instances the safety of themachine depends upon the opening of the booster-generator circuit themoment the motor portion ceases to drive it.

A further illustration of the advantage of opening the circuit uponunderloads is apparent in the charging and operation of storagebatterysystems, wherein a drop of voltage in the main generator may cause thestorage batteries to reverse the current therethrough, thereby drivingthe generator as a motor.

In such cases it is desirable (even though a shunt-wound generator isemployed which will in the instance under consideration not change itsdirection of rotation when driven as a motor) to open thegenerator-circuit when the current becomes zero.

In accordance with the preferred embodiment of my invention I provideacircuitbreaker which combines in one instrument means for opening thecircuit upon overloads or short circuits, as well as means for openingthe circuit on underloads or when the current becomes zero.

Generally speaking, my invention consists, in its preferred form, of anarmature pivotally mounted a short distance from one end thereof, thusforming two lever-arms, the normal position ofthe armature beingsubstantially horizontal. A movement or partial rotation of the armaturein one direction is occasioned by overloads and in an opposite directionby underloads or open circuit, the armature upon a sufficient movementin either direction operating a tripping device or catch to release theswitch-arm, which is thereupon automaticallyoperated bya spring to openthe circuit or otherwise render the operation of the boostergeneratorinefiective.

To reduce the number of ampere-turns required in operating the armature,I provide a closed magnetic circuitincluding the armature. The closedmagnetic circuit prevents scattering of lines of force to a largeextent, thereby making the action of the device more positive. Theaction of the armature is controlled, preferably, by means of springsacting in conjunction with the magnet.

I will describe an embodiment of my invention as applied moreparticularly to boosters by reference to the accompanying drawings, inwhich- Figure 1 is a front View, partly in section, of my improvedapparatus, its circuit connections being indicated diagrammatically.Fig. 2 is a side View thereof.

Like characters of reference indicate like parts in the two views.

A main generator 1 is shown as supplying current to the mains 2 2 thevoltage of the current wherein is to be raised, a booster consisting ofa motor portion 3 and a generator portion 4 being employed for thispurpose. The motor is in shunt of the mains 2 2, acircuit-breaker 5 anda switch 6 being included in the same bridge with the motor. Theseries-generator portion 4 of the booster is included in series with themains 2 2 through a switch 7 and a switch or circuit-breaker 8. Theconducting-strip 9 of the circuit-breaker is shown to be included in themain circuit at the terminals 10 11, the said conductingstrip beingsupplied with a carbon contactbreak, as is well known in the art. Thecontact portion 9 is secured to a pivot-ally-mount-.

ed or swinging handle 12, which is held in its closed position by meansof a catch 13, engaging a projection 14 of the handle 12. The pivotallymounted catch or detent 13 is brought out of engagement with theprojection 14 by means of a tripping-rod 15, made, preferably, of brass,which is operated by the movement of an armature 16.

I preferably include the armature 16 in a magnetic circuit consisting ofthe core 17 and the angular or L-shaped magnetic strip 18, through whichportion 18 the lines of force pass from one end of the core 17 to thearmature, the lines of force returning to the core through the armature.This magnetic circuit is thus practically closed. In the embodimeutshown I preferably employ two coils for energizing the magnetic circuit,one of which, 19, is included in series with the circuit to be opened,the other coil, 20, being preferably included in the shunt-circuit ofthe lield of motor 3.

1 preferably pivotally mount the armature 16 between its ends upon thebent strip 18 in such manner as to provide an extending arm 21, whichprojects beyond the portion 18.

The tripping-arm 15 preferably passes.

through the core 17 and rests normally upon the armature 16 out ofoperative engagement with the catch 13. The extending arm 21 of thearmature is in engagement with an arm 22, pivotally engaging one end ofanother arm 23, rotatably secured at its other end to a fixed pivot. Thearm 23 is preferably provided with a circular opening, through whichpasses the arm 15, the said arm being adapted to move vertically in saidopening. I preferably provide the arm 15 with a collar 31, placedslightly above the arm 23, normally out of engagement therewith andslightly removed therefrom.

The projecting arm 21 of the armature is provided with a lug 24, whichis normally in engagement with an angle-piece 25, upon which a force isexerted upwardly by a spring 26, whose tension may be suitably variedas, for instance, by means of a nut 27 and screw 28. The upward movementof the angle-piece 25 is limited by a stationary support 29, therebydetermining the normal condition of the armature 16. I employ a secondspring 30, preferably weaker than the spring 26, for the purpose ofreinforcing gravity to insure the release of the armature when themagnetic pull is not sufficient to hold it in its normal position.

The operation of the device will now be clear. When no current traversesthe coils 19 and 20, the armature 16 will drop, due to the combinedaction ofgravity and of the spring 30. The arm 22 will then be in itsuppermost position, as will the arm 23. The arm 23 is thereby broughtinto engagement with the collar 31, thereby raising the tripping-arm 15and placing the catch 13 in such a position that it will not engage theprojection 14. When the catch is in this position, the switch obviouslycannot be locked in a closed position, as the catch will not engage thesame, the spring 32 throwing the switch open when released.

The coil 19 in series with the mains is composed of but few turns ofwire or bar, which are alone insufficient to raise the armature toeffect the engagement of the catch with the projection 14 on the breakeror switch, sothat even if the breaker or switch he closed and currentthreads the said coil the catch 13 will not hold it in place. The coil20 has a sufficient number of turns so that the ampereturns thereofcreate a field strong enough to bring the armature to its normalposition, as indicated in the drawings. When the armature assumes thisposition, which it does when conditions are normal, the arms 23 and 22are lowered out of engagement with the collar 31 upon the arm 15, thusreleasing the catch 13 and permitting it to engage .the projection 14when the breaker is normally closed. The arm 15 now rests upon thearmature, but is not raised sufficiently to trip the catch 13. The arm15 is in the form of a plunger extending through the core of the magnet.Another important feature of this construction is now apparent in thatthe booster-circuit cannot be closed unless ,the motor-circuit isalready closed, so that there is no danger that the generator 4 willoperate as a motor. A sudden overload will cause the armature to beattracted suddenly, due to the increased magnetism created by the coil19, thus raising the arm 15 and releasing the catch 13. A magneticcircuit of comparatively low reluctance is provided by the use of theangular piece 18, and the ampere-turns required to energize the armatureare thereby greatly reduced.

An underload or break in the motor-circuit will release the armature,which, reinforced by the spring 30, raises arms 22 and 23, therebytripping the catch 13 and opening the circuit. The resistance offered bythe armature to the attractive power of the coils depends, of course,upon the tension of the spring 26, which may be adjusted for the amountof overload upon which the breaker is to open the circuit.

the respective circuits protected by either of the circuit-breakers 5and 8 when either of the breakers has operated to open either circuit.

I have shown a speed-controlling device 34 in series with the field ofthe motor 3, which speed-controlling device is used for weakening orstrengthening the field of such motor to increase or decrease its speed,thereby to cause a more efiective regulation of the system.

I have herein shown and particularly described the preferred embodimentof my invention; but I do not wish to be limited to the precisearrangement shown, as my invention is susceptible of many modifications.

Having thus described my invention, I claim as new and desire to secureby Letters Patent-- 1. In a circuit-breaker, the combination with theswitch member thereof, of an electromagnet having suitable circuitconnections for increasing its effective energization upon overload andpermitting of effective deenergization upon underload, a single armaturefor the electromagnet normally held in an intermediate position, and asingle means for holding the switch in a closed position, the saidarmature being adapted when further attracted by the electromagnet uponoverload to operate said means to release the switch, and being furtheradapted when released by the electromagnet upon underload also tooperate said means to release the switch, substantially as described.

2. In a circuit-breaker, the combination with a switch, of a detent 'fornormally securing the same in a closed position, an electromagnet, anarmature therefor, and mechanism interposed between the armature andde-. tent, normally permitting the detent to retain the switch in aclosed position, said mechanism being adapted to be operated by thearmature when further attracted by the 616C, tromagnet upon theoccurrence of an overload to operate the detent and release the switch,and being adapted also to be operated by the armature when released uponthe occurrence of underload to operate the detent and release theswitch, substantially as described.

3. In a circuit-breaker, the combination with a switch, of a detent fornormally securing the same in a closed position, an electromagnet, anarmature therefor which is pivotally'mounted between its ends, an adjusting-spring acting upon the armature on one side of a pivot andcooperating with the electromagnet when normally energized for holdingthe armature in an intermediate position, the said electromagnet actingupon the armature on the other side of its pivot, and mechanismintervening between the armature and detent, said mechanism beingoperated by the armature when further attracted by the electromagnet inopposition to said spring to operate the detent and release the switch,said mechanism being also operated when the armature is released by theelectromagnet to operate the detent and release the switch,substantially as described.

4. In a circuit-breaker, the combination with a switch, of a detent fornormally securing the same in a closed position, an electromagnet, anarmature therefor which is pivotally mounted between its ends, anadjusting-spring acting upon the armature on one side of its pivot andcooperating with the electromagnet when normally energized for holdingthe armature in an intermediate position, the saidelectromagnet actingupon the armature on the other side of its pivot, mechanism interveningbetween the armature and detent, said mechanism being operated by thearmature when further attracted by the electromagnet in opposition tosaid spring to operate the detent and release the switch, said mechanismbeing also operated when the armature is released by the electromagnetto operate the detent and release the switch, and a second springlocated upon the same side of the. armature pivot with the aforesaidspring for insuring the positive'withdrawal of the armature whenreleased by the electromagnet, substantially as described.

5. In a circuit-breaker, the combination with a switch, of a detent fornormally securing the same in a closed position, an electromagnet, anarmature therefor, an adjustingspring cooperating with the electromagnetwhen normally energized forholding the armature in an intermediateposition, and mechanism intervening between the armature and detent,said mechanism being operated by the armature when further attracted bythe electromagnet in opposition to said spring to operate the detent andrelease the switch, said mechanism being also operated when the armatureis released by'the electromagnet to operate the detent and release theswitch, substantially as described.

6. In a circuit-breaker, the combination with a switch, of a detent fornormally securing the same in a closed position, an electromagnet, anarmature therefor, an adjustingspring cooperating with the electromagnetwhen normally energized for holding the armature in an intermediateposition, mechanism intervening between the armature and detent, saidmechanism, being operated by the armature when further attracted by theelectromagnet in opposition to said spring to operate the detent andrelease the switch, said mechanism being also operated when the armatureis released by the electromagnet to operate the detent and release theswitch,

and a second spring for insuring the positivewithdrawal of the armaturewhen released by the electromagnet, substantially as described.

7. In a circuit-breaker, the combination,

with a switch, of a detent for normally secur- IIO ing the same in aclosed position, an electromagnet, an armature therefor, anadjustingspring cooperating with the electromagnet when normallyenergized for holding the armature in an intermediate position,mechanism intervening between the armature and detent, said mechanismbeing operated by the armature when further attracted by theelectromagnet in opposition to said spring to operate the detent andrelease the switch, said mechanism being also operated when the armatureis released by the electromagnet to operate the detent and release theswitch, and a second spring, located upon the same side of thearmature-pivot with the aforesaid spring for insuring the positivewithdrawal of the armature when released by the electromagnet,substantially as described.

8. In a circuit-breaker, the combination with the switch member thereof,of a detent for normally securing the same in a closed position, anelectromagnet provided with a fixed magnetic core, an armature, a fixedmagnetic portion 18 for completing the magnetic circuit between one endof said core and the armature, said armature being adapted to moveaxially of said magnet, and means whereby a movement in either directionof said armature from its normal position is adapted to efiect therelease of the detent from the switch,substantially as described.

9. In a circuit-breaker, the combination with the switch member thereof,of a detent for normally securing the switch in a closed position, anelectromagnet, a pivoted armature therefor, an arm 15 interveningbetween the armature and detent and adapted for engagement with thearmature upon one side of its pivot,mechanism intervening between saidarm and a portion of the armature upon the other side of its pivot, anda spring cooperating with the electromagnet when normally energized tohold the armature in an intermediate position, the said armature whendrawn farther toward the magnet serving to engage the said arm tooperate the detent and release the switch, and when released by themagnet serving through the agency of the said intervening mechanism alsoto operate the detent and release the switch, substantially asdescribed.

10. In a circuit-breaker, the combination with the switch memberthereof, of a detent for normally securing the switch in a closed aposition, an electromagnet, a pivoted armature therefor, an arm 15intervening between the armature and detent and adapted for engagementwith the armature upon one side of the pivot, mechanism interveningbetween said arm and the portion of the armature upon the other side ofits pivot, said mechanism comprising aswingin arm 23 having engagementwith the arm 15 and a second arm 22 linked to the arm 23 and thearmature, and a spring cooperating with the electromagnet when normallyenergized to hold the armature in an intermediate position, the saidarmature when drawn farther toward the magnet serving to engage the saidarm to operate the detent and release the switch, and when released bythe magnet serving through the agency of the said intervening mechanismalso to operate the detent and release the switch, substantially asdescribed.

11. In a circuit-breaker, the combination with the switch memberthereof, of a detent for normally securing the switch in a closedposition, an electromagnet, a pivoted armature therefor, an arm 15intervening between the armatureand detent and adapted for engagementwith the armature upon one side of its pivot, mechanism interveningbetween said arm and the portion of the armature upon the otherside ofits pivot, said mechanism comprisinga swinging arm 23 having engagementwith the arm 15 and the second arm 22 linked to the arm 23 and thearmature, a spring cooperating with the electromagnet when normallyenergized to hold the armature in an intermediate position, the saidarmature when drawn farther toward the magnet, serving to engage thesaid arm to operate the detent and release the switch, and when releasedby the magnet serving through the agency of the said interveningmechanism also to operate the detent and release the switch, and anadjusting-spring cooperating with the magnet when normally energized tohold the armature in an intermediate position, substantially asdescribed.

12. In a system of electrical distribution, the combination with acircuit, of a switch for controlling the continuity thereof, a detentfor normally securing the switch in a closed position, an electromagnetconnected in the circuit, an armature for the electromagnet, foroperating the detent to efiect the release of the switch, anadjusting-spring cooperating with the electromagnet to hold the armaturein a normal position, the said spring serving to determine the degree ofenergization in the magnet necessary for the operation of the armature,the said spring having separable engagement with the armature, and meanspermitting the armature when released to be disengaged from the spring,said armature when released also serving to operate the detent torelease the switch, substantially as described.

13. In a system of electrical distribution, the combination with acircuit, of a switch for controlling the continuity thereof, a detentfor normally securing the switch in a closed position, an electromagnetconnected in the circuit, an armature for the electromagnet, foroperating the detcnt to effect the release of the switch, an adjustingspring cooperating with the electromagnet to hold the armatureinanormal position, the said spring serving to determine the degree ofenergization in the magnet necessary for the operation of the armature,the said spring having separable engagement with the armature, and meanspermitting the armature when released to be disengaged from the spring,said armature when released also serving to operate the detent torelease the switch, and an additional spring for insuring the withdrawalof the armature from the magnet when released, substantially asdescribed. IO

In witness whereof Ihereunto subscribe my name this 28th day of October,A. D. 1899. CLARENCE H. NORWOOD. Witnesses:

GEORGE L. CRAGG, MAX ZABEL.

